Japanese Patent No. 3867107 discloses a method of using a pulse laser beam for dicing of a semiconductor substrate. This method forms an altered region inside a work piece by means of an optical damage produced by a pulse laser beam. Further, the work piece is cut based on this altered region.
According to a conventional technique, formation of the altered region is controlled using, for example, energy of a pulse laser beam, a spot diameter and a relative movement speed of the pulse laser beam and a target object as parameters.
Further, like a LED (Light Emitting Diode) which has a reflection layer, a metal film such as copper is formed on a surface of a work piece in some cases. There is a method of performing abrasion process of a metal film and an underlying semiconductor or insulator substrate at the same time to cut the work piece using a laser. However, the abrasion process have problems such as generation of scattering objects and a degradation of performance like a loss in brightness of LEDs in a cut surface after dicing.
Another method is to perform a first procedure such as etching only to remove a metal film when a work piece has a metal film, then perform second procedure to form an altered region inside the work piece and cut the work piece. In this case, there is a problem of an increase in the number of procedures for dicing.